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1ba3fc90be
Make shared_objects a StringArrayHashMap so that deduping does not need to happen in flush. That deduping code also was using an O(N^2) algorithm, which is not allowed in this codebase. There is another violation of this rule in resolveSymbols but this commit does not address it. This required reworking shared object parsing, breaking it into independent components so that we could access soname earlier. Shared object parsing had a few problems that I noticed and fixed in this commit: * Many instances of incorrect use of align(1). * `shnum * @sizeOf(elf.Elf64_Shdr)` can overflow based on user data. * `@divExact` can cause illegal behavior based on user data. * Strange versyms logic that wasn't present in mold nor lld. The logic was not commented and there is no git blame information in ziglang/zig nor kubkon/zld. I changed it to match mold and lld instead. * Use of ArrayList for slices of memory that are never resized. * finding DT_VERDEFNUM in a different loop than finding DT_SONAME. Ultimately I think we should follow mold's lead and ignore this integer, relying on null termination instead. * Doing logic based on VER_FLG_BASE rather than ignoring it like mold and LLD do. No comment explaining why the behavior is different. * Mutating the original ELF symbols rather than only storing the mangled name on the new Symbol struct. I noticed something that I didn't try to address in this commit: Symbol stores a lot of redundant information that is already present in the ELF symbols. I suspect that the codebase could benefit from reworking Symbol to not store redundant information. Additionally: * Add some type safety to std.elf. * Eliminate 1-3 file system reads for determining the kind of input files, by taking advantage of file name extension and handling error codes properly. * Move more error handling methods to link.Diags and make them infallible and thread-safe * Make the data dependencies obvious in the parameters of parseSharedObject. It's now clear that the first two steps (Header and Parsed) can be done during the main Compilation pipeline, rather than waiting for flush().